Isotope Hydrology of Dripwaters in a Scottish Cave and Implications for Stalagmite Palaeoclimate Research L

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Isotope hydrology of dripwaters in a Scottish cave and implications for stalagmite palaeoclimate research L. Fuller, A. Baker, I. J. Fairchild, C. Spötl, A. Marca-Bell, P. Rowe, P. F. Dennis

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L. Fuller, A. Baker, I. J. Fairchild, C. Spötl, A. Marca-Bell, et al.. Isotope hydrology of dripwaters in a Scottish cave and implications for stalagmite palaeoclimate research. Hydrology and Earth System Sciences Discussions, European Geosciences Union, 2008, 5 (2), pp.547-577. hal-00298932

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Papers published in Hydrology and Earth System Sciences Discussions are under Isotope hydrology of open-access review for the journal Hydrology and Earth System Sciences cave dripwaters L. Fuller et al.

Isotope hydrology of dripwaters in a Title Page Scottish cave and implications for Abstract Introduction stalagmite palaeoclimate research Conclusions References Tables Figures

L. Fuller1, A. Baker1, I. J. Fairchild1, C. Spotl¨ 2, A. Marca-Bell3, P. Rowe3, and ◭ ◮ P. F. Dennis3 ◭ ◮ 1School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK Back Close 2Department of Geology and Palaeontology, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria Full Screen / Esc 3School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK

Received: 6 December 2007 – Accepted: 27 January 2008 – Published: 3 March 2008 Printer-friendly Version Correspondence to: I. J. Fairchild ([email protected]) Interactive Discussion

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547 Abstract HESSD Dripwater hydrology and hydrogeochemistry is particularly useful to constrain the meaning of speleothem palaeoclimate archives, for example using δ18O signatures. 5, 547–577, 2008 Here, we calibrate the relationship between δ18O in precipitation, percolation waters 5 and contemporary calcite deposits, at Tartair cave, Sutherland, NW Scotland, an At- Isotope hydrology of lantic site sensitive to regional changes both of temperature and precipitation. Monthly cave dripwaters precipitation displayed a 7.1‰ range in δ18O, a negative linear relationship with rainfall amount, and no correlation with temperature. Autogenically-derived cave percolation L. Fuller et al. waters show little variation in δ18O during the same period and their annual weighted 10 mean is the same as that of the local precipitation. This evidence together with hydrological data and electroconductivity values indicates that percolation waters are well Title Page 18 mixed and dominated by stored water. Calculated values of δ O of calcite deposited Abstract Introduction in this cave environment indicate that the cave deposits are forming close to isotopic equilibrium and kinetic eﬀects are negligible. Comparison of a high-resolution δ18O sta- Conclusions References 15 lagmite record with the instrumental record of climate indicates that isotopically heavy Tables Figures values are reﬂective of relatively cold, dry conditions (and vice-versa for warm, wet condition) and hence that stalagmite oxygen isotopes provide an appropriate means of ◭ ◮ investigating the palaeoclimate in this location. ◭ ◮ 1 Introduction Back Close

20 The hydrological behaviour of small water volumes becomes particularly important Full Screen / Esc when they feed, and hence control the composition of growing calcareous deposits (speleothems) in karstic cavities. Speleothems are recognised as important continen- Printer-friendly Version tal archives of palaeoenvironmental information: they can be accurately dated using U-series techniques and their subterranean location means that they can accumulate Interactive Discussion 18 16 25 undisturbed for thousands of years. Their O/ O ratios can be used to reconstruct climate, although the rationale used can sometimes be complex and in need of further EGU testing (McDermott, 2004; Fairchild et al., 2006a). Major long-term shifts in δ18O can 548 sometimes be shown to be directly controlled by changing climate systems, indepen- dent of details of the cave environment (e.g. Wang et al., 2001). More usually, in order HESSD for this isotopic information to be utilized, an understanding of how these surface cli- 5, 547–577, 2008 mate signals are transmitted from meteoric precipitation to a speleothem via the soil 5 and groundwater system is essential (Fairchild et al., 2006a; Mickler et al., 2006). There are two major forcing factors external to the cave environment which can Isotope hydrology of change the 18O/16O ratio of calcite deposits: a change in the isotopic composition cave dripwaters of the precipitation feeding the speleothem, or a change in cave temperature. The oxy- 18 ff L. Fuller et al. gen isotopic composition of precipitation (δ Oppt) in di erent regions can be controlled 10 by the extent of temperature-related Rayleigh fractionation in the atmosphere, or may inversely correlate with the amount of rainfall, or show more complex effects, includ- Title Page ing controls by moisture source (Rozanski et al., 1993; Hoffman et al., 1998; Mook, 2000). The western seaboard of Europe displays complex controls such that changes Abstract Introduction in δ18O over time cannot be predicted from first principles because the relationship Conclusions References 15 between isotopic composition, synoptic weather processes, and climatic modes have

been incompletely explored. For example, in the UK there is normally a relationship Tables Figures between seasonality of temperature and summer and winter δ18O signatures (Darling

and Talbot, 2003), but such a correlation does not imply a simple causality (Treble et ◭ ◮ al., 2005a). The second control on calcite 18O/16O ratio is cave temperature which, 20 away from the entrance, is very close to the mean annual air temperature (MAT) out- ◭ ◮ side the cave (Wigley and Brown, 1976). An increase in cave temperature will lead to Back Close calcite becoming isotopically lighter. 18 16 Speleothem O/ O is also susceptible to local forcing factors. Processes such as Full Screen / Esc transpiration from vegetation above the cave (Williams and Fowler, 2002) and vegeta- 25 tion change over time (Baldini et al., 2005), evaporation of soil waters (Bar-Matthews Printer-friendly Version et al., 1996; Denniston et al., 1999), and mixing within the karstic aquifer (Williams and Fowler, 2002; Yonge et al., 1985) have all been shown to play a role in changing Interactive Discussion the isotopic composition between rainfall and the emerging cave drip waters. The inﬂu- ence of the karst system upon drip hydrology in turn aﬀects the majority of geochemical EGU

549 signals preserved in the subsequently deposited stalagmite calcite, the route taken by the percolating water being of primary importance. Physical characteristics of cave HESSD percolation waters are diverse (e.g. Gunn, 1981; Mangin, 1975; Atkinson, 1977) and 5, 547–577, 2008 can be classified for example in terms of mean and variance of discharge (Friederich 5 and Smart, 1982). Conceptually this can be related to varying inputs from conduit, fracture and matrix porosity in a triple-porosity aquifer (Tooth and Fairchild, 2003; Fairchild Isotope hydrology of et al., 2006b). Nevertheless, the biphase (air-water) nature of the feeding system, cave dripwaters pressure variations, and geometrical complexities result in significant non-linear be- haviours of dripwaters (Destombes et al., 1997; Genty and Deflandre, 1998; Baker and L. Fuller et al. 10 Brunsdon, 2003), including inter-annual variability (Baldini et al., 2006). The hydrology of stalagmite feeding percolation waters must be monitored in order to understand Title Page the nature of the percolation water and its evolutionary pathway (reservoirs, residence times, response to periods of heavy rainfall such as flow switching, or drought), as well Abstract Introduction as identifying any offset in composition from that of atmospheric precipitation. Conclusions References 15 Few studies have monitored cave systems in sufficient detail to understand and

correctly interpret the controlling inﬂuences, although it has been found that in mid- Tables Figures latitudes cave drip waters generally reﬂect the mean annual isotopic composition of the

precipitation in the local area (Caballero et al., 1996; Williams and Fowler, 2002; Yonge ◭ ◮ et al., 1985). Where drip discharge varies little and seepage flow can be inferred, no 18 20 seasonal variation in δ O is found, whereas when a component of fracture-fed flow is ◭ ◮ present, such variations should be present (e.g. Fairchild et al., 2006a, 2006b) and in- Back Close deed have been identified in both dripwaters (e.g. van Beynen and Febbroriello, 2006) and speleothems (Treble et al., 2005b). Full Screen / Esc In the study presented in this paper, we have gone beyond previous work by com- 25 paring the isotopic composition of drips in the modern cave with a high-resolution Printer-friendly Version δ18O record from an annually-laminated speleothem fed by one of the studied drips which allowed comparison with the instrumental climate record and hence permitted Interactive Discussion a more thorough test of the suitability of stalagmites from this site for palaeoclimate determination. EGU

550 2 Study site HESSD The study cave is in the Assynt area, located on the North Atlantic seaboard of NW Scotland (Fig. 1). Based on 1971–2000 averages, the regional climate is oceanic with 5, 547–577, 2008 >1900 mm rainfall, 250–270 rain days per year, 4–6 snow days, and an average of ◦ 5 77% cloud cover annually (Proctor et al., 2000). Mean annual air temperature is 7.1 C Isotope hydrology of (Fig. 2). The Assynt area shows a relationship between precipitation and the winter cave dripwaters North Atlantic Oscillation (NAO) Index , and temperature and ocean circulation via the North Atlantic drift (Colman, 1997; Hurrell, 1995). The NAO is a large-scale fluctuation L. Fuller et al. in atmospheric pressure between the subtropical high pressure system located near 10 the Azores in the Atlantic Ocean and the sub-polar low pressure system near Iceland and is quantified in the NAO Index, which is the pressure difference between the two. Title Page

NW Scotland displays higher mean annual precipitation occurring during years with Abstract Introduction a more positive winter NAO index associated with a stronger westerly circulation and higher frontal rainfall (Proctor et al., 2000, 2002). Annual stalagmite growth bands from Conclusions References 15 the study site have been used to reconstruct past rainfall patterns (Proctor et al., 2000, Tables Figures 2002), northern hemisphere temperature (Smith et al., 2006) and snow cover (Baker et al., 2002). ◭ ◮ The studied cave chamber is within the Cnoc nan Uamh (Gaelic for Cave Knoll) cave system (National Grid Reference NC276206, Lawson, 1988), situated 3 km east ◭ ◮ 20 of Inchnadamph and 220 m above OD (Fig. 1). The entrance is through a stream pas- sage close to a waterfall which inspired the name Uamh an Tartair (Roaring Cave) and Back Close

we use Tartair as the generic site name. Tartair is developed in Cambro-Ordovician Full Screen / Esc dolomite, dipping at shallow angles, and containing a thin igneous sill; bedrock is over- lain by peat. It is situated within the Traligill Basin, a peat dominated catchment (near- Printer-friendly Version 25 basal radiocarbon peat age above the cave of 2130±180 cal years BP) (Charman et al., 2001). Cnoc nan Uamh is small, shallow and complex cave system with three Interactive Discussion known entrances (Lawson, 1988). Water to this cave is supplied both autogenically (from seepage water derived directly from the peat covered surface) and allogenically EGU

551 (by an active underground stream which runs through the cave system). The Grotto is a well-decorated chamber ∼40m from the main cave entrance, and ∼10 m below the HESSD surface; it contains a high density of drip sites with a high soda straw density. In the 5, 547–577, 2008 Grotto area various inlets supplied by autogenic percolation water were selected for 5 monitoring; all of these actively depositing soda straw stalactite and underlying stalagmite deposit. Previous unpublished monitoring by one of us (AB) in the 1990s found the Isotope hydrology of ◦ mean annual temperature and relative humidity to be 7.1 C and >98%, respectively. cave dripwaters In the current period of monitoring, the temperature range determined from Tinytag ◦ ◦ monitors left in the Grotto was 4.8 to 9.5 C, with a mean of 7.2 C. L. Fuller et al.

10 3 Materials and methods Title Page Monthly bulk precipitation samples for isotopic analysis were collected from Inch- Abstract Introduction nadamph (3 km from the cave), using a plastic rain gauge, 0.5 m above ground level; paraﬃn oil was added to prevent evaporation. Each sample was taken on the last Conclusions References day of the month from November 2003–November 2005, but there were two missing Tables Figures 15 months in the second year of sampling. Cave drip water samples were collected from thirteen, hydrologically diverse drip sites over two hydrological years, at a resolution of two to three months. Drip waters ◭ ◮

were collected in high density polypropylene (HDPE) bottles over a period of 24–28 h; ◭ ◮ after collection they were sealed and refrigerated until analysis. Ancillary information 20 collected includes the drip interval (time between drips) and electroconductivity (EC), Back Close ◦ the latter using a WTW Multi 340i instrument, automatically correcting data to 25 C Full Screen / Esc (±0.5%). Ionic analyses (Fuller, 2007) confirm that EC is a good proxy for the total ion content derived from carbonate dissolution, i.e. dissolved calcium, magnesium and bicarbonate concentrations. Printer-friendly Version 25 Oxygen and hydrogen isotope measurements of waters were carried out at the Interactive Discussion 18 University of East Anglia using CO2-equilibration for δ O (precision 0.06‰) and by reduction using glassy carbon chips in continuous flow for δD measurements EGU (procedure modified from Begley and Scrimgeour (1997). Each groundwater sample 552 was replicated and an internal laboratory reference water was measured after every third sample. External precision was 2‰. HESSD The isotopic ratio of the contemporary calcite was measured at the University of 5, 547–577, 2008 Innsbruck, Austria. Calcite was sampled at high resolution from two Tartair sta- 5 lagmites SU96-7 and SU03-2 (whose drip waters have also been collected), using a micromill system, using continuous trenches, with a resolution of 0.1 mm in the Isotope hydrology of growth direction. The drilled stalagmite powders were then analyzed for δ18O using cave dripwaters a continuous-flow isotope-ratio mass spectrometer; for analytical details see Spotl¨ and Vennemann (2003). L. Fuller et al. 10 Isotope values are reported in delta units, which are permil deviation of the isotopic ratio from a standard: Title Page δ (in ‰) = ((R − R )/R ).1000 (1) sample standard standard Abstract Introduction

where R is the ratio of heavy to light isotope. The standard for reporting water Conclusions References isotopes is Vienna standard mean ocean water (V-SMOW) and for oxygen is calcite is Tables Figures 15 Vienna Pee Dee Belemnite (V-PDB). Precipitation and temperature data for Stornoway (see Fig. 1 for location) from AD 1873 to 2006 were obtained from the UK meteorological oﬃce. This was correlated ◭ ◮

with existing precipitation and temperature data (AD 1963–AD 1996) for Knockanrock ◭ ◮ (National Grid Reference NC187088, Fig. 1), 80 km SE of Stornaway and 12 km SW 20 of the Tartair site at a similar altitude and aspect. A positive linear relationship was Back Close found between Stornoway and Knockanrock for both temperature (r=0.99) and precipitation (r=0.84), both signiﬁcant at the 99.9% conﬁdence interval (Proctor et al., 2000). Full Screen / Esc This relationship was then used to calculate Knockanrock precipitation and temperature from July 1874 to the present (November 2003 to December 2005 shown in Fig. 2). Printer-friendly Version

25 The soil moisture budget was calculated from these data using the equation of Thorn- Interactive Discussion thwaite (1948). Temperature in the Tartair Grotto was logged from November 2003 to ◦ November 2005 using Tinytag Plus temperature loggers (sensor accuracy of 0.2 C) EGU programmed to record temperature at 15 min intervals. 553 4 Results HESSD 4.1 Isotopic composition of precipitation 5, 547–577, 2008 18 18 The mean annual δ O of the local precipitation (δ Oppt) over the 2-year collection 18 − period is given in Table 1. For each year the mean δ Oppt is 6.6‰, although there Isotope hydrology of 5 is more variation during the first year (7.1‰) than the second (3.7‰). The data shows cave dripwaters some evidence of seasonality; during the first year this is highlighted by the difference between the summer (−5.7‰) and winter (−7.5‰) mean values. The annual amount- L. Fuller et al. weighted δ18O value for Inchnadamph precipitation is −7.1‰. This is 1.7‰ heavier 18 than the amount weighted value of δ Oppt calculated for the nearest Global Network Title Page 10 of Isotopes in Precipitation (GNIP) site at Altnabreac, Caithness (Fig.1), which existed

for a 13 month period from 1980 to 1981 (Kay et al., 1984). Abstract Introduction A strong linear relationship exists between δ18O and δ2H in Inchnadamph monthly precipitation (r=0.98), demonstrated by the linear regression shown in Fig. 3, which Conclusions References represents the local meteoric water line (LMWL). The Global Meteoric Water Line Tables Figures 15 (GMWL) is also shown in Fig. 3. The Inchnadamph LMWL slope (7.05) is similar to other UK sites, for example 7.02±0.10 for Wallingford (GNIP, 2002) and 6.32±0.79 for ◭ ◮ Altnabreac (GNIP, 2002). ◭ ◮ 4.2 Percolation water hydrology and ion content Back Close The drip water inlets monitored within the Grotto area of Cnoc nan Uamh cave system Full Screen / Esc 20 are hydrologically diverse with a large range in mean discharges by a factor of nearly ffi 1000 (Table 2). The coe cient of variation (CVQ) the quotient of the standard deviation and the mean discharge expressed as a percentage, provides a suitable dimensionless Printer-friendly Version assessment of discharge variability (Friederich and Smart, 1982), whereas the maxi- Interactive Discussion mum discharge (Qmax) reflects the transmission capacity. In the classification updated 25 by Baker et al. (1997), the Tartair drips are all in low Q categories, being either max EGU seepage flow where CVQ is <50%, otherwise seasonal drips, the latter being indicative 554 of a more seasonal or “flashy” response to surface events such as high rainfall and a tendency to stop flowing during dry periods (Baker et al., 1997), during which the HESSD limestone unsaturated zone is decoupled from rainfall input, and inlets are fed from 5, 547–577, 2008 storage (Smart and Friederich, 1987; Williams and Fowler, 2002). It is notable that 5 the dripsite corresponding to our studied stalagmite, SU96-7, has a combination of a very slow drip rate and the lowest CVQ value of 6% (Table 2) indicative of a large stor- Isotope hydrology of age component which feeds the drip throughout periods of drier weather. Maximum cave dripwaters discharges measured significantly underestimate the true figures since the cave was not accessible during heavy rainfall events and peak snowmelt. However only a minor L. Fuller et al. 10 component of stalagmite growth would occur during the wet events that have not been directly observed, and so the isotopic data of the water should be more representative Title Page from this perspective. The electroconductivity data display a limited range of mean values (Table 2), con- Abstract Introduction sistent with the observed supersaturation of all the drips. There is no universal rela- Conclusions References 15 tionship between hydrology and ion content, although most seasonal drip sites display

greater electroconductivity variation. Most sites also display a negative relationship of Tables Figures electroconductivity and discharge, consistent with some dilution by a quickflow com- ffi ffi ponent. The slow driprate of site 96-7 made it di cult to collect su cient sample for ◭ ◮ EC measurement, but three observations lay well within the range of other samples. 20 In summary, the low variability of electroconductivity values points to the dominance of ◭ ◮ storage flow and the greater variation in discharge is therefore likely to reflect mainly Back Close piston flow accelerating the discharge of stored water, together with a small quickflow component. Full Screen / Esc

4.3 Oxygen isotope composition of cave percolation waters Printer-friendly Version 18 25 The lightest δ O value recorded for drip water is −7.66‰ and the heaviest is −5.99‰ Interactive Discussion (Table 3), and the range of values recorded is quite muted, from 0.36‰ at S2 to 1.19‰ ff at S5. There does not appear to be any overall di erence between drip sites classified EGU as “seepage flow” and those termed “seasonal”. The total range of all drip sites is 555 1.67‰ over the two year monitoring period. The mean of the δ18O of drip sites during the first monitoring year (2003–2004) is −7.18‰, identical within error with the mean of HESSD − 7.09‰ during the whole monitoring episode. Several points should be borne in mind 5, 547–577, 2008 when making comparison between precipitation and percolation water composition. 5 Firstly, the sampling visits were not monthly in resolution. Secondly the cave drip water samples analyzed are grab samples of water at the time of the field visit and not Isotope hydrology of monthly bulk samples. Thirdly the field visits are biased to spring/summer times when cave dripwaters access to the cave system is less likely to be prevented by adverse weather conditions. L. Fuller et al. The inaccessibility of the cave during high rainfall events further biases the δ18O data 10 of the cave drip sites. Nevertheless, it is remarkable that the mean percolation values

the same as the annual mean amount-weighted value of precipitation (Table 1). Title Page A time-series plot of all the cave drip site δ18O throughout the surveillance period is given in Fig. 4. A number of points are worth noting. Firstly the δ18O of the cave Abstract Introduction drip sites appear to vary synchronously through time. Monitoring visits with the least 18 Conclusions References 15 drip water δ O variation occur at the end of the driest period (July 2004): this could be indicative of overwhelming reliance on stored water by all cave drip water sites Tables Figures at this time. The range of δ18O values displayed by the drip waters is signiﬁcantly attenuated when compared to those of the local precipitation and show little (much ◭ ◮ reduced) seasonality (Fig. 4d). This suggests that cave drip waters are well mixed and ◭ ◮ 20 that the bulk of the water is stored in the overlying karst for periods in excess of 1 year.

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5 Discussion Full Screen / Esc 5.1 Relationship with climate Printer-friendly Version

In this section, we examine whether the composition of atmospheric precipitation has a Interactive Discussion relationship to climate and whether such a relationship is likely to be stationary. There is 18 25 no correlation between the monthly δ O values during the two year sampling period ppt EGU and either the local temperature or the North Atlantic Oscillation (NAO) index. However, 556 18 the δ Oppt shows a negative linear correlation with local precipitation amount, with an r-value of −0.42 which is statistically significant at the 0.01 level. Isotopically less HESSD negative values occur during the summer months when monthly precipitation totals are 5, 547–577, 2008 lower (Fig. 2) and vice versa. This manifestation of the “amount effect” probably relates 5 to the behaviour of synoptic weather systems, but has not been investigated further. In contrast to this record, there is a positive (r=0.47) and statistically significant corre- Isotope hydrology of 18 cave dripwaters lation between the monthly temperature and δ Oppt for Valentia, Ireland (1960–2000), a site similar to Assynt in terms of latitude and proximity to the North Atlantic. This L. Fuller et al. suggests that a longer monitoring period is required to reveal a temperature influence 10 on isotopic composition. One way we can examine the adequacy of the monitoring

length in Assynt is to perform a moving correlation on a longer data series and assess Title Page whether the r-value observed between variables during any 24 month window differs significantly to that overall. For this we used the continuous 20-year data set for GNIP Abstract Introduction site Wallingford (Fig. 1), Central England (Fig. 5), since there are gaps in the Valentia 18 Conclusions References 15 record. The r-values for the long-term (20-year) relationship between δ Oppt and temperature (r=0.53) and precipitation (r=−0.47) are represented by the thick horizontal Tables Figures lines. However, Fig. 5 highlights that for any shorter period at a given monitoring site the shorter term (c. 12–24 month) mean can vary significantly. For example, in period ◭ ◮ 1 (c. 1987–1989) in Fig. 5, if a monitoring study had been performed during this time 18 ◭ ◮ 20 the relationship between δ Oppt and climate (monthly PPT amount and T) would be ff very di erent to both the long-term 20-year relationship and that which would be estab- Back Close lished during another shorter time-slice e.g. period 2 (1994–1997). In period 1 there is a positive relationship with precipitation amount and a weaker positive correlation with Full Screen / Esc temperature, whereas in period 2, there is a stronger negative correlation to precipi- 25 tation amount and a stronger positive relationship with temperature. In summary, the Printer-friendly Version non-stationary relationships of δ18O with climate parameters in the UK context implies that empirical correlations must be used and modern speleothems can be used for this Interactive Discussion purpose. EGU

557 5.2 Contemporary calcite HESSD In this section, we explore whether the modern precipitates in the cave have an equilibrium composition as predicted from cave temperature and isotopic composition of 5, 547–577, 2008 the dripwaters. From the range of measured air temperatures within the Grotto (Ta- 18 5 ble 4) and the range of δ O measured from drip sites SU96-7 and SU03-2 (Table 3), Isotope hydrology of 18 18 a predicted range of δ O for calcite (δ Oc) deposited under these conditions can be cave dripwaters 18 calculated (Table 5). These values are compared to actual values of δ Oc of the top 1 mm of two Cnoc nan Uamh stalagmites. Stalagmite SU96-7 (Proctor et al., 2000) L. Fuller et al. was actively growing in 1996 when collected. Stalagmite SU03-2 from the same cave 10 system was actively growing when collected in 2003. The top 1mm from SU96-7 represents calcite deposited between AD 1960 and 1996, a period of 36±1 years (Proctor Title Page et al., 2000). A lamina count on the top of stalagmite SU03-2 (unpublished data) con- Abstract Introduction firms that this sample was deposited more recently and in a much shorter time period of approximately 9-10 years (between ∼AD 1995 and 2003). Conclusions References 18 15 The predicted O calculated using mean annual air temperature and the mean δ c Tables Figures annual δ18O of the drip waters is −5.7‰ (Table 5). This compares with the measured 18 − − δ Oc of 5.1‰and 5.3‰ for stalagmites SU96-7 and SU03-2 respectively (Table 6). ◭ ◮ The calcite values are closer to the δ18O of calcite predicted using cave minimum tem- ◦ perature (4.8 C). This may suggest that a significant proportion of the deposited calcite ◭ ◮ 20 occurs during colder winter months. This would be logical since cave air CO concen- 2 Back Close tration is lower during winter time leading to higher supersaturations for calcite (Fuller, ff 18 2007). Elsewhere, small (less than 1‰), but systematic o sets to higher δ Oc val- Full Screen / Esc ues have been interpreted as non-equilibrium deposition (McDermott et al., 2005), and larger kinetic effects were found in a Caribbean cave by Mickler et al. (2006). Alterna- Printer-friendly Version 25 tively, if the experimental data of Friedman and O’Neil (1977) are used for calibration, a predicted mean calcite value of −5.0‰ is found suggesting equilibrium deposition. Interactive Discussion However in any case, the cold cave temperatures (minimizing evaporation), the steady non-flashy nature of the cave drip waters and the thick peat vegetation cover above the EGU

558 cave suggests that in this cave such kinetic eﬀects on δ18O are likely to be minimal. HESSD 5.3 The sensitivity of δ18O to record climate conditions 5, 547–577, 2008 18 Using the monitoring data, the sensitivity of δ Oc to changing meteorological conditions over the instrumental period (1874 AD–present) can be tested. Firstly, the annual Isotope hydrology of 18 5 weighted mean δ Oppt for each year is calculated. This is done using the corrected cave dripwaters Stornoway temperature and precipitation series (Proctor et al., 2000) which extend back from the present to 1879 AD and the multiple linear regression equations found L. Fuller et al. 18 between δ Oppt and climate at our ﬁeld site (based on 2-year monitoring period) and Valentia (IAEA GNIP site), based on a longer though discontinuous 44-year monitoring Title Page 10 period.

The regression equations for the two locations are as follows: Abstract Introduction 18 = − × − Inchnadamph : δ Oppt 0.015 PPT amount 3.92 (2) Conclusions References

18 = × − × − Tables Figures Valentia : δ Oppt 0.199 T 0.008 PPT amount 6.28 (3)

Using the monthly climate data from AD 1879 to present (Proctor et al., 2000), the ◭ ◮ 18 15 monthly and annual δ Oppt from AD 1879 to present are hindcast. Because it has 18 18 ◭ ◮ already been shown that the mean annual δ Ow is close to mean annual δ Oppt this value is inserted together with mean annual temperature into the equation of Kim Back Close 18 and O’Neill (1997). Figure 6 shows the results in comparison with δ Oc data from stalagmite SU96-7 at an average resolution of 2.5 years. The stalagmite chronology Full Screen / Esc 20 has been derived by cross-correlation with the annual fluorescent lamina width time series (Proctor et al., 2000). A close similarity of the absolute values hindcast from Printer-friendly Version both Valentia and the local rainfall, and measured in the stalagmite, can be observed. 18 Interactive Discussion The δ Oc values display a slight trend towards lighter values over time, with a visually a closer match provided by Eq. (3) from the Valentia data than Eq. (2) from the local EGU 25 data, at least for the first half of the twentieth century. However, the local calibration is 559 more limited since it depends mostly on rainfall variability, given that the 2-year calibration period (n=22) was too short to capture any significant temperature variation. The HESSD short local observation period also contributes to the width of the error bars associated 5, 547–577, 2008 with the hind-cast; the clustering of all three time series around the mean suggests 5 that with a longer calibration period the hindcast data would still agree with stalagmite observations within errors. From this hindcasting exercise it can be seen that isotopi- Isotope hydrology of 18 cally depleted δ Oc is associated with wet and warm periods, whereas isotopically cave dripwaters heavy calcite is characteristic of dry and cold years. Calcite deposited during dry and warm, or wet and cold years lies in-between. This result is of considerable interest in L. Fuller et al. 10 improving the climatic interpretations from this site over the past millennium, since the published interpretations based on lamina thickness contrast warm, dry years (leading Title Page to enhanced growth) with cool, wet years (Proctor et al., 2000, 2002). Hence the two proxies should provide complementary information. Abstract Introduction

Conclusions References 6 Conclusions Tables Figures 18 15 Monitoring of atmospheric precipitation found a range of 7.1‰ in δ Oppt values. No 18 ◭ ◮ correlation is found between δ Oppt and temperature exists over the 2-year monitoring period, but a negative linear correlation is found with precipitation amount. Drip water ◭ ◮ 18 18 δ O is attenuated compared to δ Oppt: no drip displayed more than 1.2‰ variation in the observation period and their mean composition was close to that of the annually- Back Close 20 weighted precipitation. This indicates that the autogenic drip waters are dominated by Full Screen / Esc a large component of stored water (>1 year old) which is relatively well mixed. Drip rate monitoring and measurements of EC reinforce this observation, drip rate being particularly constant for the drip that fed stalagmite SU96-7 that was analyzed for the Printer-friendly Version hindcasting exercise. The predicted isotopic composition of calcite that should precipi- Interactive Discussion 25 tate from these cave waters under the current range of cave temperatures is 0.5–0.7‰ heavier than that of contemporary calcite of two actively growing stalagmite tips, using EGU the more recent fractionation factors. This small offset is diminished when the actual 560 18 δ Oc values are compared to predictions made using minimum temperature, consistent with other evidence of faster winter growth. Hence, if there is a kinetic isotope effect HESSD during precipitation of calcite, it is relatively small. Kinetic fractionation is not thought 5, 547–577, 2008 to play a significant role during calcite deposition due to the cold cave temperatures, 5 the steady non-flashy nature of the cave drips and the thick peat cover above the cave. Hindcasting of the isotopic composition of calcite deposited during the instrumental Isotope hydrology of climate record period (AD 1879–present) shows that this cave is sufficiently sensitive cave dripwaters and has good potential for the development of a longer series of proxy climate records L. Fuller et al. based on oxygen isotopes that will complement published interpretations derived from 10 other proxies in the studied stalagmite.

Acknowledgements. We would like to thank: G. Moseley, C. Jex, C. Smith, C. Muller, J. Moss, Title Page J. and L. Baldini for the help in the ﬁeld, C. Rix for collection of water samples, and R. John- Abstract Introduction son for providing the ﬁeld equipment. This research was funded by NERC (studentship NER/S/S/2003/11964) and formed part of the ASCRIBE project in the RAPID climate change Conclusions References 15 thematic program. Tables Figures

References ◭ ◮

Atkinson, T. C.: Diffuse flow and conduit flow in limestone terrain in the Mendip Hills, Somerset ◭ ◮ (Great Britain), J. Hydrol., 35, 93–110, 1977. Baker, A. and Brunsdon, C.: Non-linearities in drip water hydrology: an example from Stump Back Close 20 Cross Caverns, Yorkshire, J. Hydrol., 277, 151–163, 2003. Baker, A., Barnes, W. L., and Smart, P. L.: Variations in the discharge and organic matter Full Screen / Esc content of stalagmite drip waters in Lower Cave, Bristol, Hydrol. Process., 11, 541–555, 1997. Printer-friendly Version Baker, A., Proctor, C. J. and Barnes, W. L.: Stalagmite lamina doublets: a 1000 year proxy 25 record of severe winters in Northwest Scotland, Int. J. Climatol., 22, 1339–1345, 2002. Interactive Discussion Baldini, J. U. L., McDermott, F., Baker, A., Baldini, L. M., Mattey, D. P., and Railsback, L. B.: ff Biomass e ects on stalagmite growth and isotope ratios: A 20th century analogue from EGU Wiltshire, England, Earth Planet. Sc. Lett., 240, 486–494, 2005. 561 Baldini, J. U. L., McDermott, F., and Fairchild, I. J.: Spatial variability in cave drip water hy- drochemistry: Implications for stalagmite paleoclimate records, Chem. Geol., 235, 390–404, HESSD 2006. Bar-Matthews, M., Ayalon, A., Matthews, A., Sass, E., and Halicz, L.: Carbon and oxygen 5, 547–577, 2008 5 isotope study of the active water-carbonate system in a karstic Mediterranean cave: Implica- tions for paleoclimate research in semiarid regions, Geochim. Cosmochim. Ac., 60, 337–347, 1996. Isotope hydrology of Begley, I. S. and Scrimgeour, C. M.: High-precision d2H and d18O measurement for water and cave dripwaters volatile organic compounds by continuous-flow pyrolysis isotope ratio mass spectrometry, L. Fuller et al. 10 Anal. Chem., 69, 1530–1535, 1997. Caballero, E., Jimenez De Cisneros, C., and Reyes, E.: A stable isotope study of cave seepage waters, Appl. Geochem., 11, 583–587, 1996. Charman, D., Caseldine, C., Baker, A., Gearey, B., Hatton, J., and Proctor, C. J.: Paleohy- Title Page drological Records from Peat Profiles and Speleothems in Sutherland, Northwest Scotland, 15 Quaternary Res., 55, 223–234, 2001. Abstract Introduction Colman, A.: Prediction of summer central England temperature from preceding North Atlantic winter sea surface temperature, Int. J. Climatol., 17, 1285–1300, 1997. Conclusions References Darling, W. G. and Talbot, J. C.: The O & H stable isotopic composition of fresh waters in the Tables Figures British Isles. 1. Rainfall, Hydrol. Earth Syst. Sci., 7, 163–181, 2003, 20 http://www.hydrol-earth-syst-sci.net/7/163/2003/. Denniston, R. F. Gonzalez, L. A., Asmerom, Y., Baker, R. G., Reagan, M., and Bettis, E. A.: ◭ ◮ Evidence for increased cool season moisture during the middle Holocene, Geology, 27, 815– ◭ ◮ 818, 1999. Destombes, J. L., Cordonnier, M., Gadat, Y. J., and Delannoy, J. J.: Periodic and aperiodic Back Close 25 forcing of water flow through soda straw stalactites (Choranche, Vercors, France), 6th Con- ference on Limestone Hydrology and Fissured Media, Basel, Switzerland, 69–72, 1997. Full Screen / Esc Fairchild, I. J., Borsato, A., Tooth, A. F., Frisia, S., Hawkesworth, C. J., Huang, Y., McDermott, F. and Spiro, B.: Controls on trace element (Sr–Mg) compositions of carbonate cave waters: Printer-friendly Version implications for speleothem climatic records, Chem. Geol., 166, 255–269, 2000. 30 Fairchild, I. J., Smith, C. L., Baker, A., Fuller, L., Spotl,¨ C., Mattey, D., McDermott, F., and E. Interactive Discussion I. M. F.: Modification and preservation of environmental signals in speleothems, Earth-Sci. Rev., 75, 105–153, 2006a. EGU

562 Fairchild, I. J., Tuckwell, G. W., Baker, A., and Tooth, A. F.: Modelling of dripwater hydrology and hydrogeochemistry in a weakly karstified aquifer (Bath, UK): implications for climate change HESSD studies, J. Hydrol., 321, 213–231, 2006b. Friedman, I. and O’Neil, J. R.: Compilation of stable isotope fractionation factors of geochemical 5, 547–577, 2008 5 interest, US Geological Survey Professional paper 440-KK, 49 pp., 1977. Friederich, H. and Smart, P. L.: The classification of autogenic percolation waters in Karst Aquifers: A study in G.B Cave, Mendip Hills, England, Proceedings of the University of Isotope hydrology of Bristol Spelaeological Society, 16, 143–159, 1982. cave dripwaters Fuller, L.: High-resolution multiproxy geochemical Holocene climate records from 1000-year L. Fuller et al. 10 old Scottish stalagmites, Unpublished PhD thesis, University of Birmingham, UK, 2007. Genty, D. and Deflandre, G.: Drip flow variations under stalactite of the Pere Noel cave (Bel- gium), Evidence of seasonal variations and air pressure constraints, J. Hydrol., 211, 208– 232, 1998. Title Page Gunn, J.: Hydrological Processes in karst depressions, Z. Geomorphol., 25, 313–331, 1981. 15 Hoffmann, G., Werner, M., and Heimann, M.: Water isotope module of the ECHAM atmospheric Abstract Introduction general circulation model: A study of timescales from days to several years, J. Geophys. Res., 103, 16 871–16 896, 1998. Conclusions References Hurrell, J. W.: Decadal trends in the North-Atlantic oscillation – regional temperatures and Tables Figures precipitation, Science, 269, 676–679, 1995. 20 Kay, R. L. F., Andrews, J. N., Bath, A. H., and Ivanovich, M.: Groundwater flow profile and residence times in crystalline rocks at Altnabreac, Caithness, UK, in: Isotope Hydrology, ◭ ◮ IAEA, Vienna, Austria, 231–248, 1984. ◭ ◮ Kim, S. T. and O’Neil, J. R.: Equilibrium and non-equilibrium oxygen isotope effects in synthetic carbonates, Geochim. Cosmochim. Ac., 61, 3461–3475, 1997. Back Close 25 Lawson, T. J.: Caves of Assynt, The Grampian Speleological Group, Edinburgh, 1988. Leng, M. J. and Marshall, J. D.: Palaeoclimate interpretation of stable isotope data from lake Full Screen / Esc sediment archives, Quaternary Sci. Rev., 23, 811–831, 2004. Mangin, A.: Contribution a` l’etude´ des aquiferes` karstiques, Annales de Speleologie, 29, 21– Printer-friendly Version 124, 1975. 30 McDermott, F.: Palaeo-climate reconstruction from stable isotope variation in speleothems: a Interactive Discussion review, Quaternary Sci. Rev., 23, 901–918, 2004. EGU

563 McDermott, F., Schwarcz, H., and Rowe, P. J.: 6. Isotopes in Speleothems, in: Isotopes in Palaeoenvironmental Research, edited by: Leng, M. J., Springer, Dordrecht, The Nether- HESSD lands, 185–225, 2005. Mickler, P. J., Stern, L. A. and Banner, J. L.: Large kinetic isotope effects in modern 5, 547–577, 2008 5 speleothems, Geological Society of America Bulletin, 118, 65–81, 2006. Mook, W. G.: Environmental Isotopes in the Hydrological Cycle, Volume II (Atmospheric Water) UNESCO, Paris/IAEA, Vienna, 2000. Isotope hydrology of Proctor, C. J., Baker, A., and Barnes, W. L.: A three thousand year record of North Atlantic cave dripwaters Climate, Clim. Dynam., 19, 449–454, 2002. L. Fuller et al. 10 Proctor, C. J., Baker, A., Barnes, W. L., and Gilmour, M.: A thousand year speleothem proxy record of North Atlantic climate from Scotland, Clim. Dynam., 16, 815–820, 2000. Rozanski, K., Araguas-Araguas, L. and Gonfiantini, R.: Isotopic patterns in modern global precipitation, in: Climate Change in continental Isotopic Records, edited by: Swart, P. K., Title Page Lohmann, K. L., McKenzie, J., and Savin, S., Geophysical Monograph 78, Americal Geo- 15 physical Union, Washington D.C, 1–37, 1993. Abstract Introduction Smart, P. L. and Friederich, H.: Water movement and storage in the unsaturated zone of a naturally karstified aquifer, Mendip Hills, England, Conference on Environmental Problems in Conclusions References Karst Terrains and their solution, National Water Well Association, Bowling Green, Kentucky, Tables Figures 57–87, 1987. 20 Smith, C. L., Baker, A., Fairchild, I. J., Frisia, S., and Borsato, A.: Reconstructing hemispheric- scale climates from multiple stalagmite records, Int. J. Climatol., 26, 1417–1424, 2006. ◭ ◮ Spotl,¨ C. and Vennemann, T. W.: Continuous-flow isotope ratio mass spectrometric analysis of ◭ ◮ carbonate minerals, Rapdid Commun. Mass. Sp., 17, 1004–1006, 2003. Thornthwaite, C. W.: An approach towards a regional classification of climate, Geogr. Rev., 38, Back Close 25 55–94, 1948. Tooth, A. F. and Fairchild, I. J.: Soil and karst aquifer hydrological controls on the geochemical Full Screen / Esc evolution of speleothem-forming drip waters, Crag Cave, southwest Ireland, J. Hydrol., 273, 51–68, 2003. Printer-friendly Version Treble, P., Budd, W. F., Hope, P. K., and Rustomji, P. K.: Synoptic-scale climate patterns asso- 30 ciated with rainfall delta O-18 in southern Australia, J. Hydrol., 302, 270–282, 2005a. Interactive Discussion Treble, P., Chappell, J., Gagan, M. K., McKeegan, K. D., and Harrison, T. M.: In situ measurement of seasonal δ18O variations and isotopic trends in a modern speleothem from EGU southwest Australia, Eearth Planet. Sc. Lett., 233, 17–32, 2005b. 564 Van Beynen, P. and Febbroriello, P.: Seasonal isotopic variability of precipitation and cave drip water at Indian Oven Cave, New York, Hydrol. Process., 20, 1793–1803, 2006. HESSD Wang, Y. J., Cheng, H., Edwards, R. L., An, Z. S., Wu, J. Y., Shen, C. C., and Dorale, J. A.: A high-resolution absolute dated Late Pleistocene monsoon record from Hulu Cave, China, 5, 547–577, 2008 5 Science, 294, 2345–2348, 2001. Wigley, T. M. L. and Brown, M. C.: The physics of caves, in: The Science of Speleology, edited by: Ford, D. C. and Cullingford, C. H. D., Academic Press, London, 329–358, 1976. Isotope hydrology of Williams, P. W. and Fowler, A.: Relationship between oxygen isotopes in rainfall, cave perco- cave dripwaters lation waters and speleothem calcite at Waitomo, New Zealand, J. Hydrol. (NZ), 41, 53–70, L. Fuller et al. 10 2002. Yonge, C., Ford, D. C., Gray, J., and Schwarcz, H. P.: Stable isotope studies of cave seepage water, Chem. Geol., 58, 97–105, 1985. Title Page

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L. Fuller et al. Table 1. Summary data (per mil) of δ18O and δ2H (values in parentheses) in monthly precipitation at Inchnadamph. Title Page Year 1 Year 2 Abstract Introduction (Dec 2003–Nov 2004) (Dec 2004–Nov 2005) Mean −6.6 (−49.9) −6.6 (−51.5) Conclusions References Minimum −10.7 (−74.3) −8.6 (−68.8) Tables Figures Maximum −3.6 (−26.5) −5.0 (−37.1) Range 7.1 (47.7) 3.7 (31.7) Summer mean (AMJJAS) −5.7 (−43.8) −6.4 (−52.0) ◭ ◮ Winter mean (ONDJF) −7.5 (−56.0) −7.0 (−52.0) ◭ ◮ Weighted mean −7.1 (−53.3) (data incomplete) Number of data points 12 10 Back Close

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Table 2. Summary statistics for the Grotto drip site discharge data (assuming a drip volume of 0.17 cm3, as in the study of Baker et al., 1997). A coefficient of variation of <50% defines Isotope hydrology of seepage flow, whereas >50% is referred to a seasonal drip (Baker et al., 1997). Summary cave dripwaters statistics are based upon all discharge data collected including previous unpublished data of A. Baker (1997–2000). Note drip site S15 was monitored by A. Baker but was discontinued L. Fuller et al. during this study. Conductivity data is only from the current study.

Drip Mean Coeﬃcient Minimum Maximum Number of Mean Number of Title Page site (stdeviation) of discharge discharge observations (standard observations discharge variation (µl/s) (µl/s) deviation) of Abstract Introduction (µl/s) (CVQ) electroconductivity, Conclusions References µS/cm S1 36.9 (23.6) 64 1.6 90.9 11 502 (24) 9 Tables Figures S2 0.9 (0.8) 93 0.2 3.2 17 477 (14) 6 S3 0.4 (0.1) 34 0.1 0.6 17 456 (7) 9 S4 0.046 (0.1) 144 0 0.2 9 ◭ ◮ S5 0.7 (0.2) 29 0.4 1.1 15 463 (4) 7 S6 0.1 (0.1) 45 0.1 0.3 16 450 (13) 6 ◭ ◮ S7 0.4 (0.1) 14 0.3 0.6 18 454 (9) 8 S8 0.1 (0.1) 51 0 0.2 11 434 (29) 3 Back Close S12 16.4 (17.5) 107 0.5 56.0 22 483 (26) 9 S13 3.7 (6.5) 175 0.1 20.0 20 430 (25) 8 Full Screen / Esc S15 5.0 (5.3) 106 0.1 12.5 14 SU96-7 0.051 (0.0) 6 0.05 0.06 8 469 (25) 3 SU03-1 0.3 (0.1) 23 0.2 0.4 10 537 (29) 9 Printer-friendly Version SU03-2 0.5 (0.3) 56 0.1 0.8 10 547 (28) 7 Interactive Discussion

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Isotope hydrology of Table 3. Summary statistics for the δ18O of Cnoc nan Uamh cave drip sites and pool waters cave dripwaters through the monitoring period (December 2003–November 2005). L. Fuller et al.

Drip site Mean StDev Min Max Range Number of observations Title Page S1 −6.90 0.38 −7.17 −5.99 1.18 9 S2 −7.27 0.12 −7.41 −7.05 0.36 6 Abstract Introduction S3 −7.18 0.15 −7.38 −6.90 0.48 9 S4 −6.89 0.38 −7.34 −6.25 1.09 7 Conclusions References S5 −6.92 0.40 −7.23 −6.04 1.19 8 Tables Figures S6 −7.22 0.15 −7.41 −6.92 0.49 9 S7 −7.21 0.22 −7.47 −6.75 0.72 9 S8 −7.13 0.18 −7.34 −6.79 0.54 9 ◭ ◮ S12 −6.97 0.27 −7.22 −6.45 0.77 9 ◭ ◮ S13 −7.00 0.27 −7.22 −6.45 0.77 8 SU96-7 −7.07 0.36 −7.63 −6.47 1.17 8 Back Close SU031 −7.07 0.27 −7.46 −6.63 0.83 9 − − − SU03-2 7.30 0.20 7.66 7.11 0.56 7 Full Screen / Esc Cave Pool −7.15 0.29 −7.39 −6.54 0.85 7

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Table 4. Summary 12-month temperature logging data (2004–2005). Abstract Introduction

Conclusions References Monitoring location Mean Min Max Range Grotto 7.2 4.8 9.5 4.7 Tables Figures Exterior 7.2 −1.7 20.7 22.3 ◭ ◮

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18 18 Table 5. Predicted δ O values for calcite (δ Oc) on the V-PDB scale from measured temperature and water isotope composition (δ18O ) on the V-SMOW scale, calculated from w Title Page the work of Kim & O’Neil (1997). The oxygen isotope fractionation factor (α) between cal- 3 cite and water was experimentally determined by these authors to be=18.03∗(10 /T )−32.42 Abstract Introduction where T is temperature in Kelvin. Calcite composition on the V-PDB scale is given by ∗ ∗ + 18 − − Conclusions References 0.97002 (α (1000 δ Ow ) 1000) 29.98.

Tables Figures water δ18O (‰) Min (−7.66) Mean (−7.09) Max (−5.99) ◭ ◮ Min (4.8) −5.6 −5.1 −4.0 ◦ − − − ◭ ◮ Temperature ( C) Mean (7.2) 6.2 5.6 4.5 Max (9.5) −6.7 −6.1 −5.0 Back Close

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Title Page 18 Table 6. Actual δ Oc values of the top 1 mm and 0.5 mm of stalagmites SU96-7 and SU03-2. Abstract Introduction

SU96-7 SU03-2 Conclusions References (1mm) (0.5mm) (1mm) (0.5mm) Tables Figures Mean −5.1 −5.1 −5.3 −5.3 Min −5.6 −5.4 −5.5 −5.5 Max −4.8 −4.8 −5.1 −5.1 ◭ ◮

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Title Page Edinburgh Quinag (809m) Abstract Introduction Inchnadamph

Suilven Canisp (731m) (847m) Ben More Assynt Conclusions References REPUBLIC UAT Cave (998m) OF IRELAND Tables Figures ENGLAND Cul Mor & WALES (849m) Knockanrock Valentia Wallingford ◭ ◮

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2003 2004 2005 Printer-friendly Version 18 Fig. 4. Hydrological conditions and dripwater δ O values during the monitoring period. (a) Interactive Discussion and (b) are respectively monthly precipitation and soil moisture budget calculated using Thorn- thwaite equation (1948), (c) δ18O of individual drip water sites, (d) mean dripwater values (plus range indicated by dashed lines) in comparison with bulk monthly precipitation values. EGU 575 (a) HESSD 0.8 5, 547–577, 2008 0.6

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-0.8 Back Close -1.0 Period 1 Period 2 Full Screen / Esc 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 Printer-friendly Version Fig. 5. Moving correlation through the continuous 20-year (AD 1982–2002) IAEA-GNIP 18 Interactive Discussion Wallingford (Central England) data (a) shows 12-month moving correlation between δ Oppt 18 and temperature (b) shows 12-month moving correlation between δ Oppt and monthly precipitation totals. EGU

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-6 Calibrations drived from: Abstract Introduction Inchnadamph (annual climate data) Inchnadamph (decadally smoothed climate data) Conclusions References Valentia (decadally smoothed climate data) O predicted calcite ( Run C (Stalagmite data) 18 -7 d Tables Figures Two sigma error bounds -8 ◭ ◮

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18 Fig. 6. Plot showing the predicted or hindcast δ Oc values of Tartair stalagmites using cali- Full Screen / Esc brations derived from both the 2-year study site monitoring data (solid lines) and also using the 18 longer-term data recorded at the IAEA-GNIP Valentia site (dashed lines). Actual δ Oc of a Printer-friendly Version Tartair stalagmite (SU96-7) is also shown (thick black line). Interactive Discussion

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